An ionic liquid-resistance mechanism was recently identified in Enterobacter lignolyticus that consists of the EilA efflux pump, the EilR repressor and the intergenic regulatory DNA sequence (Nature Communications 5: 3490, and U.S. Patent Application Pub. No. 2014/0038848). EilR blocks transcription by binding to its operators (DNA binding sites) on the intergenic sequence. Ionic liquids act as inducer molecules by releasing EilR from the operators, enabling dynamic expression of the efflux pump in direct response to ionic liquids.